The last time a firm even came close to that was Alzheimer’s drug developer Axovant’s $315 million raise in 2015. It should be noted that Axovant’s lead pre-clinical drug at the time went on to crash and burn in spectacular fashion a little more than a year ago.

So just what does Allogene do? The firm is developing a different approach to a new form of cancer therapy called CAR-T. This kind of treatment involves re-engineering patients’ own immune cells in order to become targeted cancer killers; the modified cells are then grown in a lab, multiplied, and then re-inserted into patients, and has shown promise for some patients with deadly blood cancers. The first therapies of this kind, from Novartis and Gilead subsidiary Kite Pharma, respectively, were approved last year by the Food and Drug Administration (FDA).

Allogene’s methodology aims to create an “off-the-shelf” version of CAR-T therapy. That is, their treatment, theoretically, could be created from any immune cell donors’ cells rather than having to extract each batch individually from a patient. This would ostensibly cut down on manufacturing and production costs while reducing invasive procedures on cancer patients.

The management team at Allogene, which is led by Arie Belldegrun and David Chang, is likely a large part of the reason for the monster IPO. The pair were previously at Kite Pharma itself, which was sold to Gilead for $12 billion right ahead of its landmark CAR-T treatment approval for Yescarta. The biotech’s off-the-shelf tech was folded in from drug giant Pfizer.

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